View source for 2021 United States Senate special election in Wisconsin (ATB RP)

{{Infobox election
| election_name = 2021 United States Senate special election in Wisconsin
| country = Wisconsin
| type = presidential
| ongoing = yes
| previous_election = 2016 United States Senate election in Wisconsin
| previous_year = 2016
| next_election = 2022 United States Senate election in Wisconsin
| next_year = 2022
| election_date = {{Start date|2021|03|30}}
| turnout =
| image1 =
| nominee1 =
| party1 = Republican Party (United States)
| popular_vote1 =
| percentage1 =
| image2 =
| nominee2 =
| party2 = Democratic Party (United States)
| popular_vote2 =
| percentage2 =
| map_image =
| map_size = 220px
| title = U.S. Senator
| before_election = Jon Ronson
| before_party = Republican Party (United States)
| after_election =
| after_party =
}}

The 2021 United States Senate special election in Wisconsin will be held on March 30, 2021, to fill a vacancy in the U.S. Senate through January 3, 2022, arising from the death of Jon Ronson in January 2021.

In accordance with Wisconsin law, a special election was ordered on January 18, 2021 by the Governor of Wisconsin. The filing deadline for this election is February 2, 2021, with the special primary scheduled for March 2, 2021.

The late incumbent Republican Senator Jon Ronson was first elected in 2010. In 2016, he was reelected with 50.17% of the vote.

Wisconsin's Senate seat is expected to be one of the most heavily targeted by national Democrats for a potential flip as the party has seen considerable success in recent statewide elections, notably in the 2018 midterm elections, when Democrats won every statewide contest on the ballot in Wisconsin (including the state's other Senate seat). Furthermore, a Republican victory in this race would constitute a federal Republican trifecta and it has accordingly captured a wide nationwide following. 

==Republican Primary==
Three major candidates announced their intention to run and filed before the filing deadline.

A primary debate was held on Monday, February 15, 2021. 
===Candidates===
====Declared====
* [[Christopher Duncan Jr.]], Former Deputy White House Communications Director (2018 - 2019), nominee for the 2nd congressional district in 2020
* [[Daniel Gundersen]], Mayor of Waukesha, Wisconsin (2016 - Present) and Founder of [[Dairy Dan's]]
* [[Serah Kurian]], U.S. Representative for Wisconsin's 8th Congressional District (2013-)
===Polling===
{| class="wikitable"
|- valign=bottom
! Poll source
! Date(s)<br />administered
! style="width:100px;"| Dan Gundersen
! style="width:100px;"| Christopher Duncan Jr.
! style="width:100px;"| Serah Kurian
! Undecided
|-
| Surveylance Polling
| align=center| February 25-27, 2021
| align=center| 33%
| {{party shading/Republican}} align=center| '''34%'''
| align=center| 14%
| align=center| 19%
|-
| General Reports
| align=center| February 16-19, 2021
| align=center| 30%
| {{party shading/Republican}} align=center| '''34%'''
| align=center| 20%
| align=center| 16%
|-
| The Aggregator/CNN
| align=center| February 16-18, 2021
| {{party shading/Republican}} align=center| '''34%'''
| align=center| 33%
| align=center| 20%
| align=center| 13%
|-
| Opinionark
| align=center| February 16-17, 2021
| align=center| 29%
| {{party shading/Republican}} align=center| '''33%'''
| align=center| 23%
| align=center| 15%
|-
| Surveylance
| align=center| February 15-16, 2021
| {{party shading/Republican}} align=center| '''32%'''
| align=center| 30%
| align=center| 15%
| align=center| 21%
|-
| General Reports
| align=center| February 11-14, 2021
| {{party shading/Republican}} align=center| '''23%'''
| align=center| 21%
| align=center| 16%
| {{party shading/Undecided}} align=center| '''40%'''
|-
| Opinionark
| align=center| February 9-13, 2021
| {{party shading/Republican}} align=center| '''21%'''
| align=center| 19%
| align=center| 13%
| {{party shading/Undecided}} align=center| '''47%'''
|-
| Anderson Polling (R)
| align=center| February 6-10, 2021
| {{party shading/Republican}} align=center| '''20%'''
| align=center| 16%
| align=center| 13%
| {{party shading/Undecided}} align=center| '''51%'''
|-
| Surveylance Polling
| align=center| February 5-10, 2021
| {{party shading/Republican}} align=center| '''23%'''
| align=center| 14%
| align=center| 12%
| {{party shading/Undecided}} align=center| '''50%'''
|}

==Democratic Primary==
Two major candidates announced their intention to run and filed before the filing deadline.

A primary debate was held on Monday, February 22, 2021.
===Candidates===
====Declared====
* [[Everson Boyd]], U.S. Representative for Wisconsin's 3rd congressional district (1997 - Present), Former Secretary of Labor (1993 - 1997)
* [[Natasha Gauthier]], Attorney General of Wisconsin (2019 - Present),  Former District Attorney for Milwaukee County (2011 - 2018)

===Polling===
{| class="wikitable"
|- valign=bottom
! Poll source
! Date(s)<br />administered
! style="width:100px;"| Everson Boyd
! style="width:100px;"| Natasha Gauthier
! Undecided
|-
| General Reports
| align=center| February 16-19, 2021
| align=center| 26%
| {{party shading/Democratic}} align=center| '''30%'''
| {{party shading/Undecided}} align=center| '''44%'''
|-
| General Reports
| align=center| February 11-14, 2021
| align=center| 24%
| {{party shading/Democratic}} align=center| '''27%'''
| {{party shading/Undecided}} align=center| '''49%'''
|-
| Opinionark
| align=center| February 9-13, 2021
| align=center| 21%
| {{party shading/Democratic}} align=center| '''25%'''
| {{party shading/Undecided}} align=center| '''54%'''
|}
{{hidden begin|titlestyle=background:#cff|title=Hypothetical polling|contentstyle=border:solid 1px silver; padding:8px; background:white;}}
{| class="wikitable"
|- valign=bottom
! Poll source
! Date(s)<br />administered
! style="width:100px;"| Everson Boyd
! style="width:100px;"| Someone Else
! Undecided
|-
| Surveylance
| align=center| February 1-13, 2021
| {{party shading/Democratic}} align=center| '''23%'''
| align=center| 10%
| {{party shading/Undecided}} align=center| '''65%'''
|}
{{hidden end}}

==General Election==
===Predictions===
===Polling===
{{Graph:Chart
 | hannotatonslabel=50%
 | hannotatonsline=50
 | width = 750
 | height= 450
 | type = line
 | interpolate = bundle
 | xType = date
 | xAxisAngle = -40
 | yAxisTitle = % Support
 | yGrid = yes
 | yAxisMin = 0
 | linewidth = 2
 | x = 2021/01/21, 2021/01/22, 2021/01/24, 2021/01/25, 2021/01/27, 2021/02/01,  2021/02/02, 2021/02/04,  2021/02/06,  2021/02/09,  2021/02/11
 | y1 = 
41, 45, 47, 48, 42, 47, 47, 45, 42, 43, 47
<!-- Dems -->
 | y2 = 
44, 43, 43, 45, 43, 44, 45, 46, 44, 43, 47
<!-- Rep -->
<!-- Others -->
 | colors = #3333FF, #E81B23,
 | showSymbols = 0.4,0.4,0.4
 | symbolsShape = circle
}}
{| class="wikitable" style="text-align:center;font-size:90%;line-height:17px"
|+
!Source of poll<br />aggregation
!Dates<br /> administered
! class="unsortable" | Generic<br />Republican
! class="unsortable" | Generic<br />Democratic
!class="unsortable" |Undecided
!Margin
|-
|The Aggregator
|Until February 14, 2021
|44.1%
|{{party shading/Democratic}}|'''44.9%'''
|10.8%
|{{party shading/Democratic}}|'''Democratic +0.8'''
|}

{| class="wikitable"
|- valign=bottom
! Poll source
! Date(s)<br />administered
! style="width:100px;"| Generic<br />Republican
! style="width:100px;"| Generic<br />Democratic
! Undecided
|-
| General Reports
| align=center| February 11-14, 2021
| align=center| '''47%'''
| align=center| '''47%'''
| align=center| 6%
|-
| Opinionark
| align=center| February 9-13, 2021
| align=center| '''43%'''
| align=center| '''43%'''
| align=center| 14%
|-
| Surveylance Polling
| align=center| February 5-13, 2021
| {{party shading/Republican}} align=center| '''44%'''{{efn|name=undetermined|Poll Actual result: 44.5%}}
| align=center| 42%
| align=center| 14%{{efn|name=undetermined1|Poll Actual result: 13.5%}}
|-
| Goldwater Institute
| align=center| February 4-6, 2021
| {{party shading/Republican}} align=center| '''46%'''
| align=center| 45%
| align=center| 9%
|-
| Stuyvesant Polling
| align=center| February 2-3, 2021
| align=center| 45%
| {{party shading/Democratic}} align=center| '''47%'''
| align=center| 8%
|-
| General Reports
| align=center| February 1-5, 2021
| align=center| 43%
| {{party shading/Democratic}} align=center| '''47%'''
| align=center| 9%
|-
| Opinionark
| align=center| January 27-28, 2021
| {{party shading/Republican}} align=center| '''43%'''
| align=center| 42%
| align=center| 15%
|-
| General Reports
| align=center| January 24-27, 2021
| align=center| 45%
| {{party shading/Democratic}} align=center| '''48%'''
| align=center| 7%
|-
| Surveyor (D)
| align=center| January 24-26, 2021
| align=center| 43%
| {{party shading/Democratic}} align=center| '''47%'''
| align=center| 10%
|-
| Anderson Polling (R)
| align=center| January 22–25, 2021
| align=center| 43%
| {{party shading/Democratic}} align=center| '''45%'''
| align=center| 12%
|-
| Richard Pussey Pollsters
| align=center| January 21–24, 2021
| {{party shading/Republican}} align=center| '''44%'''
| align=center| 41%
| align=center| 15%
|}

{{notelist}}